Depends on whether you have an EQ mount I reckon.



I think the 36% waxing crescent Moon in the vicinity might make viewing M8 tricky. I'd prefer a 3-4mm exit pupil minimum with a smaller aperture. Talking of 40mm SvBony Plossls, I've pulled the trigger on a pair.

Is it my imagination or does the Amazon US site show the drawtube inverted? lol

They amended this on Amazon UK, even if they can't spell in British English!



I want to try these as a bino pair. I'm still researching the OEM, they look familiar.

 

I always associate the Lagoon and Trifid with mid summer. They reach transit in twilight for me now, so no real chance of seeing them. A broadband filter can work. I saw them earlier this year. You may need a 2mm exit pupil to see detail in the Trifid.

I was viewing the Moon earlier with the 10mm Svbony. The 6mm Omni's quite good in anything over f/6.

 

I started off in twilight with the Moon at 54x with the 90mm Orion Mak and the 23mm SvBony Aspheric. It was around Antoniadi 2 but the transparency was below average. Altitude was about 17°, azimuth 15° with the mean distance at 404,161 kilometres (Ophiuchus). I had a stacked contrast filter/Baader Fringe Killer in the diagonal nosepiece, and until it got darker, a Wratten #12 Deep Yellow (in the eyepiece) as well.


This is a simulation from the Virtual Moon Atlas (tweaked in GIMP) around 19:00 British Summer Time

I upped the magnification (now without the Wratten #12) to about 109x then 125x with the 10mm Aspheric. I could easily discern the mountain peaks in Theophilus and see the Catherina P ghost crater. Sinus Asperitatis was more nicely defined than in the simulation above with a lot of detail apparent. Good detail in the Sea of Tranquillity. The highlight for me was the bright Proclus crater. It's the second brightest crater on the Moon (after Aristarchus) as it is a younger crater and its ejecta is still very white. I believe it was a shallow impact as well from the ray streaking. The 10mm SvBony Aspheric was as sharp and bright virtually to the edge and would easily give my slightly more expensive 10mm Baader Eudiascopic a run for its money.



I'm hoping the 10mm SvBony Aspherics work well in the binoviewer.

 

From what I've read the 40mm is only 40° AFOV, which may explain a bit. I think they'll be good in the bino though. Personally, I'd go for the GSO or Meade 32mm. The GSO is especially good. There isn't that much difference between the GSO and Barsta 32mm Plossls, but the GSO has a full 50° AFOV, which the Barsta doesn't, and most people prefer it ergonomically. Plus, no undercut. If you do get a get a GSO with an undercut the lower lip is tapered (TeleVue style) so plays well with compression rings.


Celestron/Barsta 32mm Plossl (left) and Revelation/GSO (right). Ostensibly the same thing, but IMO the GSO has the edge.

 

The 32mm is really good. I have 6mm, 9mm, 12mm, 15mm, 25mm and 32mm GSO Plossls. They're all good. I really like the 30mm Vixen NPL as well.



The drawtube (brass) undercut is nice and shallow and the glass is comparable to TeleVue (possibly Lanthanum). The only thing that lets it down IMO is the plastic click-stop eyeguard. It works well and is comfortable to use, but I wonder about its long term durability.

 

I've shied away from 40mm EPs since I've found they don't show any more of the sky than a comparable 32mm EP (with the same AFOV) given the limitations of the 1.25" barrel. I have a GSO 32mm that really opened the sky for my Maks. It has the dreaded "blackout" issue but once you get used to it, your eye will automatically find the sweet spot. I use my reflector (with a BST flat-field 19mm EP) though when I want a more expansive field, but I do like my GSO 32!

 

40mm Plossls can be hard work, it's the only way for me to get a 3.1 mm exit pupil on my 102mm, f/12.7 Mak though. I think this is probably the lowest magnification (32.5x) I can get on the Mak before I can see the obstruction.

I'm hoping the 40mm SvBony Plossls will enable me to utilise the Baader UHC-S on M42 with my WO binoviewer.

 

I hope the SvBony plossls work well for you. Here is my prized GSO 32mm:

 

Thanks Reggie, I'm looking forward to trying them. I think the GSO 32mm Plossl is one of the best in its class.